Process for shrink-proofing wool and woolen fabrics



Patented Sept. 12, was

- raocsss FOR snsmx-raoormc WOOL AND wooLEN FABRICS Everett N. Angus and Joseph W. Creely, Oaklyn,

- and Ralph M. Fischer, PaLerson, N. 1.; said Angus and said Creely assignors to Eavenson dr Levering Company, Camden, N. J., and said Fischer assignor to American Gyanamid Company, New York, N. Y., a corporation of Maine J No Drawing.

Application February 19, 1945, Serial No. 578,792"

Claims. (01. 28-75) This invention relates to an improved process for the control of shrinkage, felting and fullingin woolen textile materials by the application of curable resinous materials thereto. A principal object of the invention is the treatment of wool and wool-containing fibers with resins or resinforming materials by a method, which avoids loss of shrinkage control that may be caused by mechanical working of the fibers.

It is known that varying degrees of shrinkage control can be obtained by impregnating wool and woolen textile materials with curable thermosetting resins, followed by polymerizing or curing the resins in the wool to a water-insoluble condition. fabrics such as natural loose wool, yarn, threads and knitted, felted and woven cloth-have been treated by this method with various types of thermosetting resins, such as urea-formaldehyde,

machine. However. we found that most, if not all, of the shrinkage control is lost when the stock so treated is carried through a mechanical stage of manufacture, such as carding and spinning into yarn. A large number of tests conducted in this manner has shown us that the effect of mechanical processing, in which the permanent relative position of the fibers is changed. .is to partially or completely destroy the shrinkage .control that would normally be obtained, when this processing follows the curing of a thermosetting resin within the wool.

Experiments carried out with many different types of 'thermosetting resin-forming materials Both wool and wool-containing thiourea formaldehyde and melamine formaldehyde resins. In most cases the wool is impreg nated with an aquous solution, containing these or' other similar resin-forming condensation products in their uncured or monomeric condition together with a curing catalyst, after which .knittedor woven into cloth. The extent of ,damage or loss in shrinkage control apparently the wool is dried and heated for a short time at elevated temperatures, to cause polymerization or curing of the resin to a water-insoluble condition,

There are several practical advantages in ap-' or to woolen textile materials in an early,

. mechanical stage of manufacture. For example,

where the treatment takes place in the finished have shown that the results described above are. not limited to methylated methylol melamine. On the contrary, the action of any thermosetting resin capable of. reducing the shrinking, felting or fulling of wool is seriously reduced by extensive mechanical working, which results in fiber displacement. This is particularly true of the carding and spinning operations, although it is also noticeable to a somewhat lesser extent when woolen yarn, containing a cured thermosetting resin capable of imparting shrinkage control, is

bears a direct relationship to the severity and extent of fiber displacement, which the wool replying this type of shrinkage control to raw wool, v3o

softness and resiliency may frequently be lost be- 5 cause of the binding of fibers together with resin.

we have found, however, that a totally unex-' "pected problem arises, when the shrinkage control methods outlined above are applied to raw must be subjected to mechanical working in a ticularly directed.

or partly finished woolen textile materials, that 40 ceives after the thermosetting resin has been cured therein. v

Although extensive mechanical working of wool containing a fully cured thermosetting resin cured. Therefore, in accordance with our present invention, we may impregnate the wool with an unpolymerized or substantially monomeric thermosetting resin solution, then subject the wool to the necessary mechanical working incior water-insoluble condition. By this method of The nature of the problem dealt with by our 5 2 invention is most clearly explained by the following example. -If clean raw stock is impregnated with an aqueous solution of methylated methylol melamine, containing a curing accelerator such treatment, the practical advantages resulting pared woolen textiles with the resin solution are as diammonium phosphate, and then dried and cured by heating for a few minutes at 300 F., a satisfactory shrinkage control is obtained, when Judged by the-rate of increase of felt density in a miniature felting machine. A good measure of felt density was found to be the saturated wet weight. of the felted pads produced in such a retained, while-the loss ofshrinkage control resulting from mechanical working is avoidedr However, certain precautions should be observed, which will now be explained.

Since the uncured thermosetting resins. are applied preferably as dilute aqueous solutions, it is necessary to dry the impregnated wool, at least to the extent necessary for the carding, spinning and other similar manufacturingsteps to which sults when 3 it is usually subjected. We find, however, that both the control of shrinking, felting and fullin and the scuff or abrasion resistance of thewoolen textiles, are improved considerably, if the drying of the woolen textiles is completed at relatively low temperatures prior to heating at higher tem= peratures to cure the resin. Therefore, the preferred practice of our invention includes the steps of impregnating the wool with an aqueous solution of a monomeric thermosetting resin capable of imparting control of shrinkage, felting and fulling thereto, then partially or completely drying the wool, then subjecting the wool to the necessary mechanical working incident to its manufacture into yarn or knitted or woven cloth in the absence of water, then further drying the woolen textiles if necessary, and finally converting the monomeric thermosetting resin to its polymerized, water-insoluble condition.

Our invention in its broader aspects is, not limited by the type or types of thermosetting resins used to impart shrinkage control to the wool.

It is known that shrinkage control is obtainable by impregnating the wool with 3%-30%, or more,

of its dry weight of a thiourea-formaldehyde condensation product, such as dimethylol thiourea. Urea-thiourea-formaldehyde condensation products may also be used. However, considerably better shrinkage control is obtained by the use of allwlated or alcohol-reacted methylol melamines and particularly with methylated v t I I ,Clean woolen yarn of less than 0.50% grease content is treated by dipping skeins into a bath methylol melamine, and this is the preferred thermosetting resin which we employ-in practicing our invention. Quantities on the order of '2.5%-15% or more of methylated methylol melamine, based on the dry weight of the wool or wool-containing textiles, have given excellent reapplied by the process of our inven tion.

Any suitable curing method may be employed to convert the monomeric thermosetting resin be added to the impregnating bath in quantities of about 4%, based on the weight of the Alternatively, the textiles may be treated with an acidic curing agent, during or Just prior to the curing of the resin, as by. subjecting them to vapors of sulphur dioxid or other acid gases fo'l-'- lowed by heating at 200-400 F. This two-stage process, in which the curing catalyst is applied to the textiles separately. from. the monomeric resin solution, presents the further important advantage of improved bath stability; 1. e., the resin solution used to impregnate the wool is not subject to rapid deterioration during use. Thenormal life of an impregnating bath, containing an added curing catalyst, is usually not-longer than.

24 hours, after which time a fresh bath must be prepared, whereas aqueous solutions of methylated methylol melamine and other similar thermosetting resins are stable for much longer periods of time, if no curing catalyst is added.

The improved bath stability resulting from the.

two-stage method of operation constitutes another important advantage of our invention.

From the foregoing description it is apparent .that the improved process of our invention removes several present objectionable limitations in that it allows any desired further mechanical operations to be given the woolen textiles without loss of ultimate shrinkage control. Under stock produces a percentage of waste which in the case of noils might be used in the manufacture of felt. Being shrink-proof, this waste would be worthless for felt manufacture. Under th improved process of our invention, such waste could be washed to remove resins or resinforming materials and become usable without 'loss. I v

. We explain this phenomenon in the following way: When wool is treated with a resin forming mixture and then dried and cured by heatin the fibers are stiifened somewhat and set so that they have the least amount of potential energy due to strains as long as they are in the same mechanical stage of manufacture. If agitated and washed they will not move and no felting or shrinkage will occur. If, however, the

individual fibers acquire potential energy due to strains set up in them by mechanically processing the fibers into a, fabric and the fabric is washed the fibers will tend to move ,to relievethe stresses set upin them. In so moving the fibers will felt and the fabric will shrink.

The following examples illustrate the invention, percentages all being by weight:

Example 1 of the following composition at 80 F. and soaking for 1 5 minutes;

25.6% methylated methylol melamine 0.96% diammonium phosphate (catalyst) 0% .d octyl v sodium sulfosuccinate (wetting pase tl PH=A7.OF Y l v Theskeins are then" centrifuged to a wet pick up. of -50' By percentage of wet pick .up is meant v v where A=initial dry weight of skeins B=welght of skeins after soaking in the bath and centrifuging.

The skeins are dried .best at a temperature of water.

100-160 F. .to a moisture content of about 10% Theyam may then be stored up to 2 weeks and then knitted into a finished fabric. After knitting, thefinished piece may be dried I at 150 F. for' 45 minutes with an air velocity of 300 ft./min. They can then be cured at the same air velocity for 15 minutes at 200-450 F. Such a fabric is mnch'more resistant to shrinkage in washing than an untreated piece. It also has a 425 mls. formaldehyde (40% solution) 1 g. dioctyl sodium sulfosuccinate 6 g. diammonium phosphate Water sumcient to make 1 liter'of solution pH =7.0 by additionfof sodium hydroxide Example 3 Q Same as Examples 1 or 2 but omit diammonium phosphate and treat with an equal weight of sulfur dioxide gas in a closed chamber in which a suitable fan is enclosed for circulating air containing the proper amount of sulfur dioxide. This sulfur dioxide treatment is postponed until after the piece is knitted and is applied just before drying and curing the resin.

This change in procedure is advantageous in several respects. The bath used in impregnating the wool with a resin-forming dispersion is stabilized by omitting the catalyst. It can be kept for a long time without spoiling. The treated wool can be kept for a longer time after impregnating and drying and before curing. Better'shrinkage control is obtained using sulfur dioxide or other acid gaseous catalysts as compared with a catalyst such as diammonium phosphate which is used in the resin form dispersion. I

Example 4 Bcoured raw stock of grease content prefer-' claim and desire to protect by Letters Patent of the United States is:

1. A process for controlling the shrinking, felting and fulling of wool which comprises impregnating raw wool with from 2.5% to 30% of its weight of an uncured thermosetting resin selected from the group consisting of ureaformaldehyde,- thiourea-formaldehyde and melamine-formaldehyde resins in the form of an aqueous solution, drying, carding and spinning the impregnatedwool and finally heating the wool at a temperature within the range of 200- 450 F. until the resin is converted to its cured and water-insoluble condition.

2. A process according to claim 1 wherein the wool after drying, carding and spinning is further dried to the substantial exclusion of moleture immediately prior to the final heating step.

3. A process of manufacturing a woolen fabric of reduced shrinkage upon washing which comprises impregnating raw wool with from 2.5% to 30% of its weight of an uncured thermosetting resinselected from the group conlilting of urea-formaldehyde, thiourea-formal- 6 dehydeand melamine-formaldehyde resins in the form of an aqueous solution, drying, carding and spinning the wool into yarn, converting the yarn into fabric, and heating the fabric at a temperature within the range of 200-450 F. until the resin is converted to its cured and water-insoluble condition.

4. A process for controlling the shrinking, felting and fulling of wool which comprises impregnating raw wool with from 2.5% to 15% of its weight of an uncured water-soluble methylated methylol melamine in the form of an aqueous solution thereof, drying, carding and spinning the impregnated wool and finally heating the wool at a temperature within the range of 200-450 F. until the resin is converted to i cured and water-insoluble condition.

5. A-process of manufacturing a woolen fabric of reduced shrinkage upon washing which comprises impregnating raw wool with; from 2.5% to 15% of its weight of an uncured watersoluble methylated methylol melamine in the form of an aqueous solution thereof, drying, carding and spinning the wool into yarn, converting the yarn into fabric, and heating the fabric at a temperature within the range of 200-450 F. until the resin is converted to its cured and water-insoluble condition.

' EVERETT N. ANGUS. JOSEPH W. CREELY. RALPH M. FISCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,566 Johnstone Nov. 21, 1944 1,673,797 Brown June 19, 1928 2,050,156 Borghetty Aug. 4, 1936 2,121,006 Bener June 21, 1938 2,161,805 Dreyfus June 13, 1939 2,329,622 Johnstone Sept. 14, 1943 a, FQREIGN PATENTS Number Country. Date 437,642 1 Great Britain Nov. 4, 1935 OTHER REFERENCES "Journal of the Society of Dyers and Colourists, vol. 58, No. 12, Dec. 1942. Article by H. Phillips, pages 245-253. Copy in Scientific Library. T. P. 890. S8.

American Dyestulf Reporter, vol. 33, Dec. 18, 1944; Article by J. Edward Lynn, pages FEM-P559. Copy in Scientific Library. 

1. A PROCESS FOR CONTROLLING THE SHRINKING, FELTING AND FULLING OF WOOL WHICH COMPRISES IMPREGNATING RAW WOOL WITH FROM 2.5% TO 30% OF ITS WEIGHT TO AN UNCURED THERMOSETTING RESIN SELECTED FROM THE GROUP CONSISTING OF UREAFORMALDEHYDE, THIOREA-FORMALDEHYDE AND MELAMINE-FORMALDEHYDE RESINS IN THE FORM OF AN AQUEOUS SOLUTION, DRYING CARDS AND SPINNING THE IMPREGNATED WOOL AND FINALLY HEATING THE WOOL AT A TEMPERATURE WITHIN THE RANGE OF 200450*F. UNTIL THE RESIN IS CONVERTED TO ITS CURED AND WATER-INSOLUBLE CONDITION. 